Silicon monocrystal wafer processing device, and method of manufacturing silicon monocrystal wafer and silicon epitaxial wafer

ABSTRACT

A silicon single crystal wafer process apparatus ( 10 ) having: a process chamber ( 11 ); a susceptor ( 12 ) which is disposed in the process chamber ( 11 ), and on an upper surface of which the silicon single crystal wafer ( 19 ) is placed; and a lift pin ( 14 ) which is provided to be capable of a going up and down operation with respect to the susceptor ( 12 ), for attaching or detaching the silicon single crystal wafer ( 19 ) to or from the susceptor ( 12 ) with the going up and down operation, in a state to support the silicon single crystal wafer ( 19 ) from a lower surface side, wherein the lift pin ( 14 ) is subjected to polishing on a contact end surface ( 14   d ) which contacts with a rear surface of the silicon single crystal wafer ( 19 ).

FIELD OF THE INVENTION

[0001] This invention relates to a silicon single crystal wafer processapparatus, a silicon single crystal wafer, and a manufacturing method ofa silicon epitaxial wafer.

BACKGROUND ART

[0002] For example, an apparatus for performing a process of a vaporphase growth or the like to a silicon single crystal wafer (hereinafter,referred simply as a wafer) is comprised that a wafer is transferredinto a process chamber to perform a process in a state of being placedon a susceptor in the process chamber, and after the process, the waferon the susceptor is transferred out of the process chamber.

[0003] In this case, there are various systems for placing the wafer onthe susceptor or taking the wafer from the susceptor. As one of them, asystem (hereinafter, referred as a lift pin system) has been well knownthat, for example, at least three lift pins or more provided to becapable of projection above an upper surface of a susceptor are operatedto project an approximately equal length to one another, a wafer istransferred onto the lift pins which were projected to make the three ormore than three lift pins support the wafer in an approximatelyhorizontal condition, and the lift pins are gone down one another insynchronization to place the wafer onto the susceptor, meanwhile theplaced wafer is gone up above the susceptor by the projection operationof the lift pins to carry the wafer out of the process chamber by acarrying apparatus (refer to Japanese Patent Application Laid Open No.205130/1997).

[0004] However, in the lift pin system described above, when a wafer isperformed mirror finished to both side surfaces of the wafer, the wafermay have a contact mark by a lift pin on a lower surface (that is, rearsurface) of the wafer and appearance of the wafer becomes bad.

[0005] This invention has been accomplished for solving theaforementioned problem. An object of this invention is to provide a liftpin system of silicon single crystal wafer process apparatus capable ofobtaining a silicon single crystal wafer with good appearance, amanufacturing method of a silicon epitaxial wafer, and a silicon singlecrystal wafer with good appearance even in the case of being attached toor detached from a susceptor in the lift pin system to perform process.

DISCLOSURE OF THE INVENTION

[0006] In order to attain the above described object, in accordance witha first aspect of this invention, the silicon single crystal waferprocess apparatus comprises: a process chamber; a susceptor which isdisposed in the process chamber, and on an upper surface of which thesilicon single crystal wafer is placed; and a lift pin which is providedto be capable of a going up and down operation with respect to thesusceptor, for attaching or detaching the silicon single crystal waferto or from the susceptor with the going up and down operation, in astate to support the silicon single crystal wafer from a lower surfaceside,

[0007] wherein the lift pin is polished on a contact end surface whichcontacts with a rear surface of the silicon single crystal wafer.

[0008] Preferably, the contact end surface is formed in an upwardlyconvex curved shape.

[0009] Preferably, the contact end surface of the lift pin is formedwith a surface roughness of 0.8 μm or less.

[0010] Further, preferably, at least the contact surface of the lift pincomprises SiC.

[0011] In accordance with a second aspect of this invention, the siliconsingle crystal wafer process apparatus comprises: a process chamber; asusceptor which is disposed in the process chamber, and on an uppersurface of which the single crystal wafer is placed; and a lift pinwhich is provided to be capable of a going up and down operation withrespect to the susceptor, for attaching or detaching the silicon singlecrystal wafer to or from the susceptor with the going up and downoperation, in a state to support the silicon single crystal wafer from alower surface side,

[0012] wherein a cylindrical member which can slidably guide the liftpin while moving upward, is fixedly provided on a susceptor supportmember, in a state to project from the susceptor support member whichsupports the susceptor, to make a contact end surface of the lift pincontact with the rear surface of the silicon single crystal wafer so asto be approximately parallel to the rear surface.

[0013] A sliding surface of the lift pin to the cylindrical member maybe polished.

[0014] According to the silicon single crystal wafer process apparatusof this invention, it can be suppressed that a contact mark by the liftpins remains on the rear surface of the silicon single crystal wafer,and it is possible to obtain the silicon single crystal wafer with goodappearance.

[0015] Hereupon, the silicon single crystal wafer process apparatus ofthis invention includes for example, a vapor phase growth apparatus forgrowing a thin film (single crystal thin film or poly crystal thin film)on a front surface of a silicon single crystal wafer in vapor phase,however, it is not limited thereto. For example, an apparatus whichperforms a prescribed heat treatment to a silicon single crystal wafermay be included.

[0016] In accordance with a third aspect of this invention, the siliconsingle crystal wafer comprises: a silicon oxide film to prevent scratchgeneration formed on a rear surface on which mirror finished wasperformed.

[0017] Preferably, the silicon oxide film has a thickness of 50 nm ormore and 200 nm or less.

[0018] In accordance with a forth aspect of this invention, themanufacturing method of a silicon epitaxial wafer comprises: a firstmirror finished step of performing mirror finished on at least a rearsurface of a silicon single crystal wafer; an oxide film formation stepfor forming a silicon oxide film on the rear surface of the siliconsingle crystal wafer; a second mirror finished step of performing mirrorfinished on a front surface of the silicon single crystal wafer; and avapor phase growth step of growing a silicon epitaxial layer on thefront surface of the silicon single crystal wafer in vapor phase, usinga vapor phase growth apparatus which comprises a lift pin for attachingor detaching the silicon single crystal wafer to or from a susceptor,

[0019] wherein the steps are performed in this order.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a cross sectional view showing a vapor phase growthapparatus as an embodiment of a process apparatus according to thisinvention;

[0021]FIG. 2 is a view showing a state where lift pins of the vaporphase growth apparatus in FIG. 1 are moved up;

[0022]FIG. 3 is an enlarged view showing a portion near a contact endsurface of the lift pin to a silicon single crystal wafer;

[0023]FIG. 4 is a plan view showing portions on the silicon singlecrystal wafer, supported by the lift pins;

[0024]FIG. 5 is a main portion enlarged view showing a lower end portionof the lift pin and a member for moving up the lift pin by supportingthe lower part thereof;

[0025]FIG. 6 is an enlarged view showing a portion near a contact endsurface of a lift pin (modified embodiment) to the silicon singlecrystal wafer;

[0026]FIG. 7 is a main portion enlarged view showing a cylindricalmember for guiding the lift pin; and

[0027]FIG. 8 is a side view showing the silicon single crystal wafer,which is formed a silicon oxide film on a rear surface.

BEST MODE FOR CARRYING OUT THE INVENTION

[0028] An embodiment according to this invention will be explainedreferring to the drawings below.

[0029] [First Embodiment]

[0030] In this embodiment, a vapor phase growth apparatus will beexplained as a preferred embodiment of a silicon single crystal waferprocess apparatus according to this invention.

[0031]FIGS. 1 and 2 show, for example, a single wafer type vapor phasegrowth apparatus 10 which is schematically comprised of a reactionchamber (process chamber) 11, a susceptor 12 which is disposed in thereaction chamber 11, and on an upper surface of which a silicon singlecrystal wafer 9 (hereinafter, also referred simply as a wafer 9) isplaced, a feed path 17 for feeding reaction gas on a front surface ofthe wafer 19 placed on the susceptor 12, a susceptor support member 13for supporting the susceptor 12, lift pins 14 which are provided in astate of penetrating from front to rear of the susceptor 12, and aremovable up and down with respect to the susceptor 12, and a lift pingoing up and down member 15 for going up or going down the lift pins 14by supporting the lift pins from a lower side.

[0032] The susceptor 12 is schematically formed in a disk shape, andcomprises a pocket 12 a on an upper surface thereof for placing thewafer 19 therein. The susceptor 12 is supported by a plurality ofsupport arms 13 a which are radially provided in the susceptor supportmember 13 from a lower side to keep the upper surface in anapproximately horizontal position.

[0033] The lift pins 14 are, for example, obtained by growing a SiC film(for example, approximately 100 μm in thickness) by CVD (Chemical VaporDeposition) on a raw material of carbon. For example, as shown in FIG.3, a lift pin 14 comprises a body part 14 a formed in a round bar shape,and a head part 14 b formed on an upper end part of the body part 14 ato support the wafer 19 from a lower surface side. The head part 14 bhas a diameter larger than that of the body part 14 a to easily supportthe wafer 19.

[0034] An upper surface (contact end surface) 14 d of the head part 14 bof the lift pin 14 is formed in a curved surface shape which is convexupward and has a gently changing curvature, and is polished.

[0035] Specifically, for example, it is preferable that the uppersurface 14 d of the head part 14 b is comprised that the upper surface14 d is pre-formed in a curved surface shape before CVD growth of a SiCfilm and is subjected to curved surface polish finished by a grinderafter CVD growth. In this case, for polishing accuracy, it is preferablethat a surface roughness is, for example, 0.8 μm and below. Forpolishing by the grinder, with regard to forming the SiC film on thesurface of the lift pin, it is preferable to polish using SiC grindstonemade from the similar material (hereinafter, named as “same materialabrasive polishing”).

[0036] By performing the same material abrasive polishing in thismanner, it can prevent that foreign material mix into a polished surfaceof the SiC film. Moreover, the lift pin 14 from which polished powder issufficiently removed is obtained by cleaning the polished surface.

[0037]FIGS. 1 and 2 show only two lift pins 14 as cross sectional views,however, the lift pins 14 are arranged in three positions at a uniformangle interval on a circumference, sharing the same center with thepocket 12 a, so that the wafer 19 is supported at the three points(refer to FIG. 4).

[0038] The susceptor 12 is provided with through holes 16 whichpenetrate the susceptor 12 a from front to rear. Each through hole 16has a head receiving part 16 a at an upper part, which is formed to havea size and a shape capable of receiving the head part 14 b of the liftpin 14. At a part lower than the head receiving part 16 a, each throughhole 16 is set to have a diameter which is smaller than that of the headpart 14 b of each lift pin 14, and is larger than that of the body part14 a. Each lift pin 14 is inserted into each through hole 16 of thesusceptor 12 from a lower end thereof, and is in a state of beingsupported by the head receiving part 16 a of each through hole 16. Thebody part 14 a of each lift pin 14 also penetrates a through hole 13 bprovided in each support arm 13 a of the susceptor support member 13.

[0039] A lift pin going up and down member 15 is gone up or down by adriving apparatus which is not shown.

[0040] The lift pin going up and down member 15 comprises a plurality ofradially extending support arms 15 a. Each support arm 15 a supports acorresponding lift pin 14 at an upper surface of a tip thereof to go upor down each lift pin 14, thereby going up or going down each lift pin14 with respect to the susceptor 12.

[0041] For example, as shown in FIG. 5, a cavity portion 15 b which iscaved in a spherical shape is formed on an upper surface of a tip ofeach support arm 15 a, whereas a lower surface of a lift pin 14comprises a supported part 14 c which is formed in a spherical shapecapable of engaging into the cavity portion 15 b. Therefore, the liftpin 14 can be positioned in the cavity portion 15 b easily.

[0042] According to the vapor phase growth apparatus 100, a siliconsingle crystal thin film is epitaxially grown on the front surface ofthe wafer 19 in a manner described below.

[0043] First, as the lift pin going up and down member 15 is moved up,each lift pin 14 is projected to an approximately equal length to oneanother above the upper surface of the susceptor 12 (the state thatthere is no wafer 19 in FIG. 2). Further, the wafer 19 is carried by ahandler which is not shown to place the wafer 19 whose front surfacebecome up on the lift pins 14 after the project operation. Therefore,the wafer 19 becomes, for example as shown in FIG. 4, the state to besupported by the three lift pins 14 which are mutually separated at anapproximately uniform interval (approximately uniform angle interval),from the lower surface side (that is, rear surface side).

[0044] Since the upper surface 14 d of the head part 14 b of each liftpin 14 is formed in a curved shape which is convex upward, and ispolished, a contact mark by the lift pins 14 is unlikely to remain onthe rear surface of the wafer 19.

[0045] Next, each lift pin 14 is gone down in synchronization with eachother as the lift pin going up and down member 15 is gone down, whileremoving the handler. The wafer 19 is gone down keeping an approximatelyhorizontal position, as the lift pins 14 are gone down.

[0046] When the lift pin going up and down member 15 is gone down to thedegree that each lift pin 14 is supported by the head receiving part 16of the upper part of each through hole 16 in the susceptor 12 withoutbeing supported by the lift pin going up and down member 15, the goingdown operation is completed.

[0047] At this stage, the head part 14 b of each lift pin 14 is receivedby the head receiving part 16 a of the upper part of each through hole16 in the susceptor 12, while the wafer 19 moves to the state to beplaced in the pocket 12 a of the susceptor 12 from the state to besupported on the head parts 14 b of the lift pins 14 (the state shown inFIG. 1).

[0048] When the wafer 19 is placed on the susceptor 12 as described, thevapor phase growth is performed.

[0049] That is, reaction gas (carrier gas and material gas) is fed fromthe feed path 17 of the upper side of the susceptor 12 while rotatingthe wafer 19 by rotating the susceptor 12 and also, heating the wafer 19from above and below by a heating apparatus (not shown) such as aninfrared ray lamp or the like, whereas purge gas is fed to the lowerside of the susceptor 12, thereby growing a silicon epitaxial layer onthe front surface of the wafer 19 in vapor phase.

[0050] When the vapor phase growth is completed, the wafer (siliconepitaxial wafer) 19 after the vapor phase growth is carried outside ofthe reaction chamber 11.

[0051] That is, the rotation of the susceptor 12 is preliminary stopped,and thereafter, each lift pin 14 is operated to project above thesusceptor 12 synchronizing with each other, by going up the lift pingoing up and down member 15. With the projection operation, the wafer 19is gone up above the pocket 12 a from inside of the pocket 12 a of thesusceptor 12. Thus, the wafer comes into the state to be supported byeach lift pin 14 from the lower surface side (the state shown in FIG.2). Then, the wafer 19 is carried by the handler which is not shown.

[0052] According to the first embodiment described above, since theupper surface 14 d of the head part 14 b of each lift pin 14 is formedin a curved shape which is convex upward, and is polished, it cansuppress that a contact mark by the lift pins 14 remains on the rearsurface of the wafer 19, enabling to obtain a silicon epitaxial waferwith good appearance.

[0053] [Modification]

[0054] The lift pins 14 are not limited to the embodiment describedabove. For example, as shown in FIG. 6, an upper surface 14 d of a headpart 14 b may be a flat surface which is polished. A polishing accuracythereof is set as described above.

[0055] In the above described embodiment, the lift pins are subjected tothe same material abrasive polishing with SiC, however, it is notlimited thereto. For example, the lift pins may be polished with amaterial such as diamond or the like which is harder than SiC. Here, itis not preferable to polish with metal, because the lift pins may beaffected by metal pollution.

[0056] [Second Embodiment]

[0057] The second embodiment also explains a vapor phase growthapparatus as a preferred embodiment of a silicon single crystal waferprocess apparatus according to this invention. The vapor phase growthapparatus in the second embodiment is same as that in the firstembodiment except points described below, thus the explanation exceptthe points described below is omitted here.

[0058] That is, the vapor phase growth apparatus in the secondembodiment, for example as shown in FIG. 7, comprises cylindricalmembers 21 which are capable to slidably guide a lift pin 14, while thegoing up operation of the lift pin 14. The cylindrical member 21slidably guides the lift pin 14, so that an upper surface 14 b of thelift pin 14 contacts with the rear surface (lower surface) of thesilicon single crystal wafer 19 in an approximately parallel condition.

[0059] The cylindrical member 21 is, for example, fixedly provided onthe susceptor support member 13 in a state to project upward anddownward from the susceptor support member 13.

[0060] The susceptor support member 13 is made from, for example,quartz, and the cylindrical member 21 is also made from, for example,quartz.

[0061] An inner diameter of the cylindrical member 21 is set to beslightly larger than a diameter of the body part 14 a of the lift pin14.

[0062] A sliding surface of the lift pin 14 (that is, a periphery of thebody part 14 a) which slides on the inner surface of the cylindricalmember 21 may be polished with a polishing accuracy similar to that inthe above described first embodiment. In this case, particles generatedby friction between the cylindrical member 21 and the lift pin 14 can besuppressed, so that a silicon epitaxial wafer reduced particle adhesionor formation of crystal defects can be obtained at high yield.

[0063] According to the second embodiment described above, since thecylindrical member 21 slidably guides the lift pin 14 while the lift pin14 is gone up, the upper surface 14 b of the lift pin 14 contacts withthe rear surface of the silicon single crystal wafer 19 in anapproximately parallel condition. Thus, it can suppress that a contactmark by the lift pins 14 remains on the rear surface of the wafer 19,enabling to obtain a silicon single crystal wafer with good appearance.

[0064] [Third Embodiment]

[0065] The third embodiment explains a silicon single crystal wafer anda manufacturing method of a silicon epitaxial wafer according to thisinvention. The explanation may be given by referring to the elements ofthe vapor phase growth apparatus 10 explained in the above firstembodiment.

[0066] First, a silicon single crystal wafer in this embodiment will beexplained.

[0067] A silicon single crystal wafer 30 in the third embodiment is, forexample as shown in FIG. 8, formed a silicon oxide film 30 a on a rearsurface which was subjected to mirror finished. The silicon oxide film30 a is formed to prevent the rear surface from scratch generation bycontacts with the lift pins 14 (for preventing scratch generation).

[0068] The silicon oxide film 30 may be formed by CVD (may be a CVDoxide film), or may be formed by heat oxidation (may be a thermal oxidefilm). However, a thermal oxide film is preferably used in view of afunction for preventing the scratch formation because a thermal oxidefilm is dense in structure in comparison with a porous CVD oxide film.

[0069] For example, if a thickness of the silicon oxide film 30 a is 50nm or more and 200 nm or less, it is sufficient, however, it is notlimited thereto. The film thickness may be more than 200 nm or less than50 nm, if the film thickness is set enough to prevent the scratchformation caused by contacts of the upper surfaces 14 d of the lift pins14 with the rear surface of the silicon single crystal wafer 30.

[0070] In the third embodiment, the upper surface 14 b of each lift pin14 of the vapor phase growth apparatus 10 may be formed in a non-curvedsurface shape which is convex upward, or may be non-polished. However,the higher the polishing accuracy is and the smoother the curvature ofthe upper surface 14 b formed to be convex upward changes, the thinnerthe film thickness of the silicon oxide film 30 a necessary forpreventing the scratch becomes.

[0071] Next, the manufacturing method of a silicon epitaxial wafer willbe explained.

[0072] First, the rear surface of the silicon single crystal wafer issubjected to mirror finished (first mirror finished step).

[0073] Next, a silicon oxide film is formed on the rear surface of thesilicon single crystal wafer (silicon oxide film formation step).Thereby, the silicon single crystal wafer 30 described above can beobtained.

[0074] Next, a front surface of the silicon single crystal wafer 30 issubjected to mirror finished (second mirror finished step).

[0075] Next, the vapor phase growth is performed by using the vaporphase growth apparatus 10 comprising the lift pins 14 by which a siliconsingle crystal wafer is attached to or detached from the susceptor 12 toepitaxially grow a silicon epitaxial layer on the front surface of thesilicon single crystal wafer 30. That is, in the order as explained inthe above first embodiment, the silicon single crystal wafer 30 isplaced on the susceptor 12 to perform the vapor phase growth, andthereafter, the silicon epitaxial wafer is carried out of the reactionchamber 11.

[0076] According to the third embodiment described above, the siliconoxide film 30 a formed on the rear surface of the silicon single crystalwafer 30 functions as a protection film, so that it can be preventedthat a contact mark by the lift pins 14 remains on the rear surface.

[0077] In the third embodiment, the rear surface of the silicon singlecrystal wafer is subjected to mirror finished in the first mirrorfinished step, however, the rear surface and the front surface may besubjected to mirror finished in the first mirror finished step.

INDUSTRIAL APPLICATION

[0078] According to the silicon single crystal wafer process apparatus,the silicon single crystal wafer, and the manufacturing method of thesilicon epitaxial wafer of this invention, it can suppress that acontact mark by the lift pins remains on the rear surface of the siliconsingle crystal wafer, enabling to obtain the silicon single crystalwafer with good appearance. Therefore, the silicon single crystal waferprocess apparatus, and the silicon single crystal wafer and themanufacturing method of the silicon epitaxial wafer of this invention,are particularly suitable for performing the vapor phase growth to forma thin film on the front surface of the silicon single crystal wafer.

1-9. Cancelled.
 10. A silicon single crystal wafer process apparatuscomprising: a process chamber; a susceptor which is disposed in theprocess chamber, and on an upper surface of which the silicon singlecrystal wafer is placed; and a lift pin which is provided to be capableof a going up and down operation with respect to the susceptor, forattaching or detaching the silicon single crystal wafer to or from thesusceptor with the going up and down operation, in a state to supportthe silicon single crystal wafer from a lower surface side, wherein thelift pin is subjected to polishing on a contact end surface whichcontacts with a rear surface of the silicon single crystal wafer. 11.The silicon single crystal wafer process apparatus as claimed in claim10, wherein the contact end surface is formed in an upwardly convexcurved shape.
 12. The silicon single crystal wafer process apparatus asclaimed in claim 10, wherein the contact end surface of the lift pin isformed with a surface roughness of 0.8 μm or less.
 13. The siliconsingle crystal wafer process apparatus as claimed in claim 11, whereinthe contact end surface of the lift pin is formed with a surfaceroughness of 0.8 μm or less.
 14. The silicon single crystal waferprocess apparatus as claimed in claim 10, wherein at least the contactsurface of the lift pin comprises SiC.
 15. The silicon single crystalwafer process apparatus as claimed in claim 11, wherein at least thecontact surface of the lift pin comprises SiC.
 16. The silicon singlecrystal wafer process apparatus as claimed in claim 12, wherein at leastthe contact surface of the lift pin comprises SiC.
 17. The siliconsingle crystal wafer process apparatus as claimed in claim 13, whereinat least the contact surface of the lift pin comprises SiC.
 18. Asilicon single crystal wafer process apparatus comprising: a processchamber; a susceptor which is disposed in the process chamber, and on anupper surface of which the single crystal wafer is placed; and a liftpin which is provided to be capable of a going up and down operationwith respect to the susceptor, for attaching or detaching the siliconsingle crystal wafer to or from the susceptor with the going up and downoperation, in a state to support the silicon single crystal wafer from alower surface side, wherein a cylindrical member which slidably guidesthe lift pin while going upward, is fixedly provided on a susceptorsupport member in a state to project from the susceptor support memberwhich supports the susceptor, to make a contact end surface of the liftpin contact with the rear surface of the silicon single crystal wafer soas to be approximately parallel to each other.
 19. The silicon singlecrystal wafer process apparatus as claimed in claim 18, wherein asliding surface of the lift pin to the cylindrical member is polished.20. A silicon single crystal wafer comprising: a silicon oxide film forpreventing scratch generation formed on a rear surface on which mirrorfinished was performed.
 21. The silicon single crystal wafer as claimedin claim 20, wherein the silicon oxide film has a thickness of 50 nm ormore and 200 nm or less.
 22. A manufacturing method of a siliconepitaxial wafer comprising: a first mirror finished step of performingmirror finished on at least a rear surface of a silicon single crystalwafer; an oxide film formation step of forming a silicon oxide film onthe rear surface of the silicon single crystal wafer; a second mirrorfinished step for performing mirror finished on a front surface of thesilicon single crystal wafer; and a vapor phase growth step of growing asilicon epitaxial layer on the front surface of the silicon singlecrystal wafer, using a vapor phase growth apparatus which comprises alift pin for attaching or detaching the silicon single crystal wafer toor from a susceptor, wherein the steps are performed in this order.